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 A230806 The smallest of 4 consecutive palindromic numbers that are all primes. 2
 1878781, 11782828711, 13828882831, 33694849633, 36331813363, 76093839067, 93121812139, 1018278728101, 1101228221011, 1200528250021, 1237788877321, 1296978796921, 1318608068131, 1449108019441, 1477968697741, 1608678768061, 1713708073171, 1792308032971 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS There cannot be 5 consecutive palindromic numbers that are all primes. The central digit of all numbers in the sequence will be 8. LINKS Shyam Sunder Gupta, Table of n, a(n) for n = 1..2166 EXAMPLE 1878781 is in the sequence because 1878781, 1879781, 1880881 and 1881881 are consecutive palindromic numbers that are all primes. MATHEMATICA a = {}; m = 0; Do[z = n*10^(IntegerLength[n] - 1) + FromDigits@Rest@Reverse@IntegerDigits[n]; If[PrimeQ[z], m = m + 1; If[m == 1, z1 = z]; If[m == 4, AppendTo[a, z1]], m = 0], {n, 1, 1000000000}] CROSSREFS Cf. A000040, A002113, A002385, A032595. Sequence in context: A251008 A064820 A032595 * A032596 A032597 A203794 Adjacent sequences: A230803 A230804 A230805 * A230807 A230808 A230809 KEYWORD nonn,base AUTHOR Shyam Sunder Gupta, Oct 30 2013 STATUS approved

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Last modified July 21 18:17 EDT 2024. Contains 374475 sequences. (Running on oeis4.)